"A few years ago, I rolled an old 401k into a Traditional IRA. Is there any way that I can now roll this IRA into my current company's 401k program?"
You couldn’t ask this question at a more opportune time as I have recently encountered this with two different clients. There is a way to roll a traditional IRA into a current 401k but that doesn’t mean it is possible in all scenarios. Fortunately, in your situation it is easy to find out. Call your current company’s plan administrator and explain to him/her exactly what you are looking to do and ask if your current 401k allows it. If it does, you are in good shape. Then ask what the process is for making that happen.
In my experience, 401k’s generally aren’t that willing to accept rollovers from traditional IRA’s though most allow for rollovers from other "old" 401k’s. I hope your experience is different. This is one of several reasons that I caution people about rolling over “old” 401k’s into traditional IRA’s in a previous blog post I did on this topic.
I hope you have better luck than my other clients. Both were unable to roll this money into their current 401k’s and it has limited some of the creative things we could do with them. If you are in doubt about what to do with your “old” 401k when leaving an employer, I strongly recommend consulting with a fee only financial planner. I do not mean to be self-promoting, but in the case of both the clients that I mentioned, they would be in much better shape today had they sought some professional guidance prior to making their decision to rollover their "old" 401k.
I hope you are able to do the rollover.